Recessed Lighting Fixture and Flexibly Attached Compact Junction Box

ABSTRACT

A recessed lighting fixture includes a lamp housing and a separate compact junction box, which contains a power supply that drives the lamp and serves in part to divide the interior cavity of the junction box into two separate wiring compartments. The junction box has two end walls spaced along an axis and a releasably secured, sleeve-like cover (side wall) surrounding and closing the cavity. The cover can be moved axially in either direction relative to the end walls to open the wiring compartments. The junction box and the lamp housing are mechanically connected only by a flexible conduit and a flexible tether, which prevents undue strain on the electrical connections between the joined components. The lighting fixture is particularly suitable for retrofit installations, especially where small-aperture downlights are desired.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from provisional application Ser. No.61/483,912, filed May 9, 2011, which is incorporated herein by referencein its entirety.

FIELD OF THE INVENTION

The invention relates to lighting fixtures and junction boxes, and torecessed lighting fixture assemblies in which the associated junctionbox is connected to the lamp housing by a flexible conduit.

BACKGROUND OF THE INVENTION

Certification standards of Underwriters Laboratories Inc. (UL) requirethat a recessed lighting fixture be designed and constructed to allowroom-side access to the junction box where the branch circuitconnections to the lighting fixture are made as well as access to anyassociated electrical component (transformer, ballast, driver, etc.).Access must be through an opening not less than six inches across. ULstandards also require that the junction box be integral to the lightingfixture or securely fastened to its enclosure or frame. If the junctionbox is attached by a flexible conduit, it must have “additional means ofsecurement.”

Many recessed lighting fixtures have their associated junction boxes andother components (transformer, ballast, driver, etc.) disposed laterallyof the housing that contains the lamp assembly. In a traditionalarrangement for lighting fixtures having an aperture of six inches orlarger, the lamp housing, the junction box and other components aresupported on a common pan or frame, which is secured to the adjacentbuilding structure (joists, ceiling grid, etc.). A releasable connectionbetween the lamp housing and the pan or frame allows the lamp housing tobe dislodged and withdrawn from the ceiling opening to permit access tothe nearby junction box and other components. In another commonarrangement, often used in retrofit applications or other situationswhere the entire lighting fixture is to be supported only by an existingceiling, the junction box and other components are supported on alaterally extending strut or arm attached to the lamp housing, usuallyforming a generally L-shaped unit. The lighting fixture is installedfrom below the ceiling through a ceiling opening that closely surroundsthe lower end of the lamp housing when fully seated. The lightingfixture is removable through the same opening for servicing and accessto the junction box. The size of the ceiling opening dictates themaximum size of the junction box and any other lighting fixturecomponent, which must fit through the opening during installation andalso during removal for servicing.

Many L-shaped retrofit assemblies can be somewhat difficult to installand remove, especially in situations where joist spacing is tight orwhere obstructions such as joist blocking, ductwork or piping arelocated close to the lighting fixture installation hole. Further, thesmall installation holes (e.g., 2⅞ inch or smaller) required for smallaperture lamp housings make junction box miniaturization challenging,especially where the junction box must house a transformer, driver orother component. When above-ceiling access is available from the roomthrough a properly sized auxiliary opening, a standard junction box canbe used. Otherwise the usual solution is to mount the transformer ordriver in an accessible remote location, which requires additional laborand materials.

SUMMARY OF THE INVENTION

One aspect of the invention concerns a compactly packaged junction boxassembly for electrically powering a load. Such an assembly comprises ahousing enclosing a cavity; a power supply within the cavity having aninput side for receiving power from a source and an output side fordelivering power to a load; and a chassis within the cavity supportingthe power supply and substantially dividing the cavity into first andsecond wiring compartments. The power supply is situated in an aperturein the chassis with the input side facing the first compartment and theoutput side facing the second compartment.

In this assembly, the power supply preferably occupies a portion of eachwiring compartment and is supported on a mounting flange at one edge ofthe aperture. The overall shape of the housing preferably iscylindrical. Openings in the housing's end walls communicate with thetwo wiring compartments to enable wiring to both sides of the powersupply.

Another aspect of the invention concerns an arrangement of junction boxfeatures that facilitate access to its interior. The arrangementincludes an axially extending support in the junction box cavitycarrying two axially spaced end walls, and a releasably secured sidewall surrounding and closing the cavity between the end walls. Whenreleased, the side wall is movable axially in either direction relativeto the end walls to open and permit access to the cavity.

This arrangement preferably includes a resiliently biased retractablestop near each end wall that engages and releasably secures the sidewall in a closed position surrounding the cavity. Each retractable stop,which may be a portion of a spring clip, preferably engages a respectiveend of the side wall when in its closed position. The overall shape ofthe junction box preferably is cylindrical. Openings in the end wallscommunicate with the cavity.

The invention also concerns a lighting fixture assembly that includes ajunction box or junction box assembly as described above flexiblyattached to a lamp housing containing a lamp assembly. A flexibleconduit interconnects the junction box and the lamp housing with wiringtherein for supplying power to the lamp assembly. A flexible tether,which preferably runs through the flexible conduit, has one end anchoredto the lamp housing and the other end anchored to the junction box. Thelength of the tether prevents undue strain on the wiring and itsconnections, and preferably prevents undue strain on the flexibleconduit.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the disclosed invention, including the bestmode for carrying out the invention, are described in detail below,purely by way of example, with reference to the accompanying drawing, inwhich:

FIG. 1 is a side elevational view of the recessed lighting fixture ofthe invention installed in and above a ceiling;

FIG. 2 is a perspective view of the lighting fixture of FIG. 1, withsome parts removed for clarity and with top housing 18 and cylindricalcover 72 shown as transparent to reveal inner details;

FIG. 3 is an enlarged perspective view of the lamp housing portion ofthe lighting fixture of FIG. 1, with top housing 18 shown astransparent;

FIG. 3A is an exploded perspective view of the upper portion of the lamphousing of FIG. 3, showing an alternative wiring arrangement;

FIG. 4 is an exploded perspective view of the lamp housing of FIG. 3;

FIG. 4A is a partial perspective view of the lamp housing of FIG. 3,shown in a disassembled state;

FIG. 5 is an enlarged perspective view of the junction box portion ofthe lighting fixture of FIG. 1 shown in a partially open condition, thecylindrical cover 72 shown as transparent;

FIG. 6 is a top perspective view of the chassis of the junction box ofFIG. 5;

FIG. 7 is a bottom perspective view of the junction box chassis of FIG.6;

FIG. 8 is a top perspective of the junction box of FIG. 5 without thecylindrical cover;

FIG. 9 is a top perspective view of the junction box of FIG. 8 takenfrom the opposite side;

FIG. 10 is a bottom perspective view of the junction box of FIG. 8;

FIG. 11 is a bottom perspective view of the junction box of FIG. 10taken from the opposite side;

FIG. 12 is a side elevational view of the junction box of FIG. 8 showingwiring in both compartments thereof;

FIG. 13 is a perspective view of the junction box of FIG. 12 showingwiring in the input (supply) compartment thereof; and

FIG. 14 is a perspective view of the junction box of FIG. 12 showingwiring in the output compartment thereof.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-5, a lighting fixture according to the inventioncomprises a lamp housing 10, a junction box assembly 40 and a flexiblemetal conduit 30 interconnecting the lamp housing and the junction boxand protecting wiring within. Lamp housing 10 comprises a metallictubular lower body 12, a finned metallic upper housing 16 and ametallic, generally square two-part top housing 18 (shown as transparentin FIGS. 2, 3 and 4). Lower body 12 houses a removable reflector 13having a bottom annular trim flange 14; and it has two tangential,oppositely directed retention springs 15 that removably secure the lamphousing 10 in a properly sized installation hole H in ceiling C, withtrim flange 14 bearing against the lower surface of the ceiling.Junction box 40 simply rests on the ceiling near the lamp housing.

Three screws 22 securely fasten the three-sided, U-shaped bottom half 20of top housing 18 to fins of upper housing 16. The inverted box-shapedtop half 24 of top housing 18 fits over and is secured to the upstandingsides of bottom half 20 by two screws 26. One end of conduit 30 isreceived in an aperture 28 in one side of top half 24 and is retainedtherein by a suitable wire-protecting metallic connector 32, such as theflanged connector disclosed in U.S. Pat. No. 4,880,387 (incorporatedherein by reference). The same or a similar connector 34 secures theother end of conduit 30 to an end of junction box 40. The conductivityafforded by these connectors enables metallic conduit 30 to provide anelectrical grounding path from lamp housing 10 to junction box 40, whichis grounded as described below.

A lamp assembly 19 is mounted to the bottom of upper housing 16 so as tobe disposed within lower body 12 when the lower body is joined to theupper housing. Light generated by the lamp assembly is dispersed and/orfocused by reflector 13, while heat generated by the lamp assembly isdissipated by the finned heat sink of upper housing 16. As used herein,“lamp assembly” means a light source of any type powered by electricity,such as an incandescent lamp (e.g., conventional tungsten filament orhalogen), a compact fluorescent lamp, an LED light engine, etc. In theillustrated preferred embodiment, the lamp assembly is an LED lightengine, such as a high output XSM LED module manufactured by Xicato(http://www.xicato.com/products.php). As shown in FIGS. 4 and 4A, upperhousing 16 is joined to lower body 12, preferably by means of externalthreads 27 on the mounting ring of lamp assembly 19, those threadsmating with internal threads 29 at the upper end of lower body 12. Theinherent adjustability of this threaded connection accommodates smallvariations in the length of reflector 13, which may be due tomanufacturing tolerances, allowing for accurate close positioning of thesmall upper-end aperture of reflector 13 relative to lamp assembly 19for proper optical performance. A nylon-tipped set screw 17 preventsrelative rotation of the threaded parts after adjustment.

Insulated conductors W in protective flexible conduit 30 emerge in tophousing 18, extend through upper housing 16 and are connected to lampassembly 19. Preferably, as seen in FIG. 3A, conductors W terminate intop housing 18 in a first connector half 21, which mates with a secondconnector half 23 wired via conductors 25 to lamp assembly 19. Such aconnector arrangement facilitates removal and replacement of lampassembly 19. Alternatively, twist-on connectors can be used in tophousing 18 to connect conductors W to conductors 25.

Conductors W emerge from the other end of conduit 30 in junction box 40,where they are connected to a power supply 42 as more fully describedbelow. Also within conduit 30 is a flexible tether 36 that emerges intop housing 18 where it is secured by a crimped eye-lug 37 riveted at 38to the top half 24 of that housing. The other end of tether 36 emergesfrom conduit 30 in junction box 40 where it is secured to junction boxchassis 44 by a crimped eye-lug 46 and a screw 47. The length of tether36 is selected such that it functions as a strain relief cable toprevent undue strain on the conductors W and their connections, andpreferably to prevent undue tensile loading on flexible conduit 30.Tether 36 preferably is conductive and preferably is made of braidedgalvanized or stainless steel. If metallic, tether 36 provides anelectrical grounding bond between lamp housing 10 and junction box 40.The preferred path of tether 36 is through flexible conduit 30 asillustrated, but the tether instead could run externally of the conduit,optionally loosely tied to the conduit by tape, nylon ties or othermeans.

Referring to FIGS. 5-14, chassis 44 closely surrounds power supply 42,which is mounted in a generally rectangular central aperture 45 in thebase of chassis 44. A broad longitudinal mounting flange 48 protrudingfrom one longer side of aperture 45 has two mounting slots 50 near itsdistal edge. Two additional mounting slots 52 are formed in the base ofchassis 44 near the proximal end of flange 48. As seen in FIGS. 5, 8 and12-14, two mounting straps 54 pass through slots 50, 52 and surroundpower supply 42 to firmly secure it in position against flange 48. Forthe sake of simplicity, mounting straps 54 are omitted from FIGS. 9-11.Nylon cable ties may be used as mounting the straps; however, anysuitable mounting hardware could be used depending on the configurationof the power supply and/or any mounting tabs it may have.

Axially spaced circular end plates 60, 62 are riveted at 63 to aperturedtabs 56, 58, respectively, at the ends of chassis 44. Each end plate hasa peripheral notch 64 that accommodates a resilient spring clip 66,which is riveted at 67 to a narrow longitudinal flange 68 protrudingfrom one edge of chassis 44. Each of the two spring clips 66 has ashoulder 70 that engages an end of sleeve-like cylindrical cover 72 (seeFIGS. 1 and 2), the two shoulders acting as opposing stops to trap thecover in a closed position closely surrounding chassis 44 and end plates60, 62. Inward finger pressure on either spring clip 66 allows itsshoulder 70 to clear the end of cover 72, which can then be slid openaxially past the depressed spring clip as shown in FIG. 5 and completelyremoved, if desired.

Any other suitable arrangement could be used instead of the illustratedspring clips to releasably maintain the cover 72 in a closed position.Such devices could be mounted on chassis 44, on one or both end plates60, 62 or on the cover 72 itself. By way of example only, each end plate60, 62 could carry a linearly or pivotally retractable member(spring-loaded or otherwise), which when extended acts as a stop againstan end of the cover 72 to keep it closed. Alternatively, one or morescrews could secure the cover to chassis flange 68 or to an adjacent tabcarried by an end plate. Furthermore, while a right circular cylinder isthe preferred shape of the junction box, the shape of the end plates andthe matching cross-section of the cylindrical cover could vary somewhatas long as the described functionality is not impaired. In order tofacilitate below-ceiling installation and removal of the lightingfixture assembly as described below, the maximum width of the junctionbox 40 should be no greater than the maximum width of the lamp housing10 (excluding retention springs 15).

Chassis 44 divides the interior of the junction box into twocompartments 80, 90 in which wiring for different voltages is separatelymaintained. In the preferred embodiment, power supply 42 is a step-downtransformer (driver) that converts line (supply) voltage fed to inputcompartment 80 to a lower voltage for powering the LED light engine oflamp assembly 19 from output compartment 90. Thus, the input leads 82 ofpower supply 42 are disposed in input compartment 80 (shown with plug-inconnectors in FIGS. 12 and 13), while the lower voltage output andcontrol leads 92 are disposed in output compartment 90 (shown withtwist-on connectors in FIGS. 12 and 14). As used herein, the term “powersupply” broadly means any device that converts, conditions or otherwisemodifies or adapts supplied electrical power for a specific load orapplication.

End plate 60 has an opening 74 through which line voltage and groundconductors (not shown) are fed to input compartment 80, which alsohouses a ground wire (see FIGS. 12 and 13) secured to chassis 44 by ascrew 77 (see FIG. 11). Through branch wiring can be accommodated viaopening 74 by using an appropriate duplex connector. End plate 62 has anopening that supports a conventional, outwardly projecting thermalprotector 76, which is connected to wiring in input compartment 80 (seeFIGS. 12 and 13). End plate 62 also has an opening 78 in which an end ofconduit 30 is received and is secured by connector 34 (see FIG. 5).Conductors W in conduit 30 thus communicate with lower voltage outputcompartment 90, where they are connected to driver output leads 92 (seeFIGS. 12 and 14). An opening in end plate 60 adjacent output compartment90 is closed by a knockout 79, which can be removed for the separateentry of low voltage control wiring, such as for a lamp dimming control.

Installation of the lighting fixture assembly is straightforward. Cover72 is released and slid open over conduit 30 in the direction of lamphousing 10 to expose input compartment 80. Supply wiring above theceiling is pulled through the fixture installation hole H, passedthrough and clamped in opening 74 (using an appropriate connector) andconnected to input leads 82 and the fixture ground wire. Cover 72 isthen slid closed and latched. Junction box 40 is then passed upwardthrough the installation hole H followed by flexible conduit 30.Junction box 40 simply rests on the upper surface of the ceiling. Withretention springs 15 squeezed around lower body 12, the lamp housing 10is pushed upwardly into the installation hole until the springs pop outabove the ceiling, locking the fixture in place. A slight clockwisetwist of the reflector 13 seats it firmly against the ceiling. Thefixture can be removed from the ceiling easily by first twisting thereflector 13 slightly counterclockwise while applying slight downwardpressure. Once the retention springs 15 are accessible, they aresqueezed together and the lamp housing is pulled down out of theinstallation hole, followed by flexible conduit 30 and junction box 40.

While a preferred embodiment has been chosen to illustrate theinvention, it will be understood by those skilled in the art thatvarious changes and modifications may be made without departing from thescope of the invention as defined by the appended claims. While thelighting fixture of the invention has been described as well-suited fora retrofit, ceiling-supported installation, the lamp housing andjunction box components could also be removably mounted on ajoist-supported pan or frame above a ceiling. Furthermore, the advantageof compactness realized by the described junction box configurationwould make it suitable for use in other applications or situations aslong as applicable electrical code requirement are observed.

1. A junction box assembly for electrically powering a load, comprising:a housing enclosing a cavity; a power supply within said cavity havingan input side for receiving power from a source and an output side fordelivering power to the load; and a chassis within said cavitysupporting said power supply and substantially dividing said cavity intoa first wiring compartment and a second wiring compartment, said chassishaving an aperture, wherein said power supply is situated in saidaperture with said input side facing said first wiring compartment andsaid output side facing said second wiring compartment.
 2. A junctionbox assembly according to claim 1, wherein said power supply occupies aportion of each of said wiring compartments.
 3. A junction box assemblyaccording to claim 2, wherein said chassis comprises a mounting flangeat one edge of said aperture abutting said power supply.
 4. A junctionbox assembly according to claim 3, wherein said power supply is securedto said mounting flange.
 5. A junction box assembly according to claim4, wherein said power supply is strapped to said mounting flange.
 6. Ajunction box assembly according to claim 2, comprising first and secondopenings in said housing respectively communicating with said first andsecond wiring compartments.
 7. A junction box assembly according toclaim 1, wherein said housing comprises two end walls at opposite endsof said chassis, and a releasably secured cylindrical sleeve surroundingsaid cavity between said end walls and movable relative to said endwalls in at least one direction to open said wiring compartments.
 8. Ajunction box assembly according to claim 7, wherein said housingcomprises at least one movable stop adapted to engage and releasablysecure said sleeve in a closed position surrounding said cavity.
 9. Ajunction box assembly according to claim 7, wherein said at least onemovable stop comprises a resiliently biased retractable stop near eachend wall for allowing selective release and opening movement of saidsleeve in either direction relative to said end walls.
 10. A junctionbox assembly according to claim 9, wherein each of said stops engages arespective end of said sleeve when in its closed position.
 11. Ajunction box assembly according to claim 10, wherein each of said stopscomprises a shoulder portion of a respective spring clip, which issupported by said chassis and extends beyond its respective end wallthrough a notch therein.
 12. A junction box assembly according to claim11, wherein said spring clips are supported by a flange at one edge ofsaid chassis.
 13. A junction box assembly according to claim 7, whereinsaid end walls are substantially circular.
 14. A junction box assemblyaccording to claim 7, wherein a first one of said end walls has anopening into said first wiring compartment, and a second one of said endwalls has an opening into said second wiring compartment.
 15. A junctionbox assembly according to claim 14, wherein said second end wall has anauxiliary opening into said first wiring compartment.
 16. A lightingfixture assembly comprising the junction box assembly of claim 1 and alamp housing flexibly attached to said junction box assembly, said lamphousing containing a lamp assembly electrically connected to said powersupply.
 17. A lighting fixture assembly according to claim 16,comprising a flexible conduit interconnecting said junction box assemblyand said lamp housing, and wiring in said flexible conduit electricallyinterconnecting said power supply and said lamp assembly.
 18. A lightingfixture assembly according to claim 17, comprising a flexible tetherhaving a first end anchored to said lamp housing, a second end anchoredto said junction box assembly and a length that prevents undue strain onsaid wiring and connections thereto.
 19. A lighting fixture assemblyaccording to claim 18, wherein said tether runs through said flexibleconduit.
 20. A lighting fixture assembly according to claim 19, whereinsaid tether has a length that prevents undue tensile loading on saidflexible conduit.
 21. A junction box enclosing a cavity, comprising: anaxially extending support in said cavity; two axially spaced end wallscarried by said support; and a releasably secured side wall surroundingand closing said cavity between said end walls, wherein said side wall,when released, is movable axially in either direction relative to saidend walls to open and permit access to said cavity.
 22. A junction boxaccording to claim 21, comprising at least one movable stop adapted toengage and releasably secure said side wall in a closed positionsurrounding said cavity.
 23. A junction box according to claim 22,wherein said at least one movable stop comprises a resiliently biasedretractable stop near each end wall for allowing release and openingmovement of said side wall in a selected direction.
 24. A junction boxaccording to claim 23, wherein each of said stops engages a respectiveend of said side wall when in its closed position.
 25. A junction boxaccording to claim 24, wherein each of said stops comprises a shoulderportion of a respective spring clip, which extends beyond its respectiveend wall through a notch therein.
 26. A junction box according to claim21, wherein said support comprises a chassis adapted to support a devicein said cavity.
 27. A junction box according to claim 26, wherein saidchassis substantially divides said cavity into two compartments.
 28. Ajunction box according to claim 26, wherein each end wall has at leastone opening therein.
 29. A junction box according to claim 21, whereinsaid side wall comprises a cylindrical sleeve.
 30. A junction boxaccording to claim 29, wherein said end walls are substantially circularand said sleeve has a substantially circular cross-section.
 31. Alighting fixture assembly comprising the junction box of claim 21 and alamp housing flexibly attached to said junction box assembly, said lamphousing containing a lamp assembly.
 32. A lighting fixture assemblyaccording to claim 31, comprising a flexible conduit interconnectingsaid junction box and said lamp housing, a power supply in said junctionbox, and wiring in said flexible conduit electrically interconnectingsaid power supply and said lamp assembly.
 33. A lighting fixtureassembly according to claim 32, comprising a flexible tether having afirst end anchored to said lamp housing, a second end anchored to saidjunction box assembly and a length that prevents undue strain on saidwiring and connections thereto.
 34. A lighting fixture assemblyaccording to claim 33, wherein said tether runs through said flexibleconduit.